Laser materials processing as known in the art and used herein refers to performance of materials processes such as cutting, welding, drilling and soldering, using a continuous wave or pulsed laser beam. The average power of such a laser beam may range from as little as approximately one watt to 100's of watts, the specific power being selected on the basis of the particular processing being performed. It is also known in the art to transmit the laser beam from the laser to the vicinity of the workpiece by means of an optical fiber. Apparatus and method for injecting a power laser beam into an optical fiber for transmission therethrough are disclosed in commonly assigned U.S. Pat. Nos. 4,564,736; 4,676,586; and 4,681,396 respectively entitled "Industrial Hand Held Laser Tool and Laser System", "Apparatus and Method for Performing Laser Material Processing Through a Fiber Optic", and "High Power Laser Energy Delivery System", the disclosures of those patents being incorporated in their entirety herein by reference.
As disclosed in the above incorporated patents, injection of the laser beam into the fiber end is accomplished by focusing the beam, by means of one or more lenses, onto the prepared input end of the fiber. Specific requirements for the size of the focused beam cone, the beam spot size as focused on the fiber end, and the fiber end preparation are described in those patents. Compliance with these requirements is necessary in order to successfully inject the laser beam into the optical fiber for transmission therethrough. Implicit in these requirements is the need to properly align the focused laser beam with the fiber end. Misalignment of the beam and fiber end will result in either inefficient or no beam transmission through the fiber. Further, where the laser beam has sufficient power, misalignment will result in damage to the fiber end thereby requiring replacement of the fiber or repair of the fiber end.
Various techniques are known in the art for aligning optical components, such as the alignment of a single core optical fiber with a focused laser beam. Such optical alignment techniques include the use of cameras, microscopes, low power aligning lasers, infrared viewing of a power laser operated at low, non-damaging power levels or some combination of these techniques. A common characteristic of these optical alignment techniques is that they are time consuming, require performance by a skilled optics technician and are based on a subjective assessment made by that technician. That is, the optics technician uses his/her skill to subjectively judge, based on observation using one of the listed alignment techniques, when the components are aligned.
The time consuming aspect of such optical alignment techniques and the need for their practice by a skilled optics technician present a problem in a manufacturing environment where laser materials processing is practiced. Upon the occurrence of each need to replace or reposition an optical fiber being injected with a laser beam, the time required to effect fiber alignment with the beam injecting apparatus represents manufacturing downtime and therefore manufacturing cost and inefficiency. This downtime is magnified by the time consuming aspects of the known optical alignment techniques as well as by being constrained by the availability of an optics technician to effect the alignment. While it is acknowledged that the known optical techniques provide accurate alignment, it would be desirable to provide a mechanical technique analogous to such optical techniques that enables positioning of a fiber to assume the precise alignment of a fiber initially installed and aligned using an optical technique. Such a mechanical technique would preferably be minimally subjective and not require practice solely by a skilled optics technician. As a result, an initial alignment using an optical alignment technique would only have to be performed once, the mechanical technique being employed for all subsequent alignments to duplicate the alignment achieved with the initial optical alignment.
One technique practiced in the art as an attempt to minimize movement of an installed fiber, and thereby hopefully promote a longer service life, is the rigid mounting of the fiber end in a coupler which in turn connects to the laser beam source. In such a case, the coupler may include the focusing apparatus which focuses the laser beam for injection. A further feature of such couplers is that the fiber is typically "potted" into the coupler, e.g. an epoxy material is flowed over a portion of the fiber and surrounding coupler environment to ensure no fiber movement once alignment is achieved. Where misalignment does occur, whether due to incorrect alignment of the fiber within the coupler, misalignment in the coupler's connection to the laser source, misalignment in the focusing lens arrangement, etc., damage to the fiber end will result where a power laser beam of sufficient energy is used or, at very least, inefficient beam transmission will result. In either event, fiber replacement will be required and because of the potting of the fiber within the coupler, the entire coupler in addition to the fiber will have to be discarded.
It is therefore a principal object of the present invention to provide apparatus and method for positioning an optical fiber for laser beam injection, in the precise location of a previously aligned fiber, which is not subject to the aforementioned problems and disadvantages.